Caption: Nanowire tweezers. Computer artwork showing nanowires (grey cylinders) surrounded by an electric field (red and yellow). The electric field, known as an optoelectronic tweezer, is able to control the direction and orientation of the nanowires. This will allow the accurate building of nanoscale devices. Nanowires are artificially grown crystal filaments that measure only a few nanometres (billionths of a metre) in diameter, and several microns (thousandths of a metre) in length. They may have applications in electronics and photonics (control of light photons), such as extremely small lasers, solar cells, switches and sensors. This research was carried out in 2008 by Peidong Yang and colleagues at the University of California, Berkeley, USA.